1. Field of the Invention
The present invention relates to a fiber crimping apparatus which is designed to give waves to the synthetic fibers formed straight by fiber drawing devices, and particularly the fiber bundles are delivered out into the stuffing box by means of two nip rollers which press against each other.
2. Description of the Prior Art
The conventional fiber crimping apparatus equipped with two nip rollers is of two kinds; the one kind, as referred to in U.S. Pat. Nos. 3,096,558, 3,137,055 and 3,248,770, is an outer contact type in which fiber bundles are passed between two rollers the outer surfaces of which are pressed against each other and rotate at the same speed; the other kind, as referred to in U.K. Pat. No. 1,408,235, is an inner contact type in which a ring roller, the inner surface of which is formed on the contacting surface, is made to contact the internally contacting roller, which has an eccentric rotating shaft and the outer surface is formed on the contacting surface and a crescent shaped stuffing box is formed between the two rollers.
The above-mentioned outer contact type conventional apparatus has a drawback that the nip zone, which is formed in the front and the rear of the roller contacting point, is too short. On the other hand, the internally contacting type has such the advantage that the nip zone can be larger. In the outer contact type conventional apparatus, the fibers tend to scatter along the rotating direction of each roller when they pass the place of contact of the rollers and enter the stuffing box. For preventing such scatter of fibers, it was necessary to fit a scraper to each roller and lead the fibers to the stuffing box exactly. But, the fibers are pressed out through a gap of the scraper at so high rate that very delicate processing and assembling adjustment were required for preventing such pressing out of the fibers. Further, because of such structure that the stuffing box situated at the rear of the rotating direction of the roller was surrounded by fixed side walls, there were such defects as the fibers fly out of the stuffing box through a gap between the side walls and the roller and/or friction heat is produced by a difference in velocity at the time when the bundles of fibers fed into the stuffing box at a high speed come in contact with the fixed side walls and thus the fibers are damaged. For that reason, it has been expected to improve the crimping apparatus in order to eliminate the abovementioned defects of the crimping apparatus of a roller system and to speed up crimping process.
This sort of drawback also exists in the internal contact roller type apparatus. That is in this type apparatus in which a crescent shaped stuffing box is formed between the two rollers that contact internally and one side of the said box which is open, is closed with a cover plate; one side out of four sides is formed by a fixed wall surface, a small gap is formed between the said cover plate and the two rotating rollers, and the abovementioned facts caused such troubles as the fiber escapes out of the box through the said gap, the flowing fibers generate heat by contacting the cover plate, all of which affect the production of uniform crimp. For this reason, there has been a problem of eliminating the drawback of mechanical fiber feeding using two rollers, of speeding-up of the crimping process and of developing an apparatus which enables production of crimped yarn of more uniform crimping and highly reliable results.